In wireless communication systems, it is often desirable to generate a quadrature local oscillator (LO) signal for either upconversion of a signal to be transmitted or downconversion of a received signal. Ideally, the quadrature LO signal includes a quadrature component (Q) that leads an in-phase component (I) in phase by 90°. However, due to factors such as a non-symmetrical layout and component mismatch, a phase error is created. For example, a phase error of 2° may be created such that the quadrature component (Q) leads the in-phase component (I) by 92° instead of 90°. The phase error limits image rejection and thus the overall performance of the transceiver.
In order to reduce the phase error of the quadrature LO signal, designers strive to provide both a symmetrical design and a symmetrical layout. However, in reality, there still remains electrical differences between the I and Q branches. Further, the fabrication process inevitably creates mismatches in components in the I and Q branches, which result in additional phase error. To reduce the phase error to an acceptable level, designers often go through a trial and error process to find a layout that reduces the phase error to an acceptable level. Thus, there remains a need for a system and method for easily correcting such phase error.